Methyl-green (MG) has been used for histochemical and cytochemical demonstration of DNA; however, it has been reported that this staining reaction requires the presence of highly polymeric DNA. The following results of our study show that the polymerization of DNA is not always necessary for the reaction.
1) MG staining solution is easily influenced by the pH, and is very stable at around pH 4.0. Intensity of the reaction of MG goes with the ascent of pH when the starting solution is fresh.
2) In the DNase-enzymatic digestion test, MG stain has thesame effect as the Feulgen reaction. MG staining also stains not only pure DNA but RNA.
3) The cytoplasm of well preserved cells is stained with MG, and this result suggests that the MG staining reaction is not influenced by the degree of polymerization of DNA.
4) MG stain is available for measuring the DNA content of the nuclei under some conditions.
